This invention relates generally to encoded sheet material, and more particularly to edge coding schemes for sheet material having information recorded thereon.
Despite the publicity about the paperless office, paper remains an important media in today""s working environment. Many efforts have been made to integrate paper documents with computer-based information systems. These efforts generally involve two scenarios. The first scenario involves scanning an existing physical document to create a digital copy, assigning a digital file name and then managing the digital copy as any other digital file. The second scenario involves creation of a physical document from an existing digital document or file such as by printing. To aid in the integration process, a barcode or a Dataglyph may be printed or otherwise attached to,a physical document. Dataglyphs are generally less visually disruptive than barcodes. Both barcodes and Dataglyphs provide a means for the computer to grasp intentionally printed information on the paper document. Since both are generally applied at the time the information is recorded on the sheet of paper (but may be applied later through the use of an adhesive label), both generally appear on the same face of the sheet of paper as the recorded information.
U.S. patent application Ser. No. 09/643,628 filed Aug. 21, 2000, Encoded Sheet Material and System for Processing (the xe2x80x9c628 applicationxe2x80x9d), which is assigned to the assignee of this application, describes a way to uniquely identify sheets of material, such as paper, using a code which may be applied on the edge of material reams, or stacks, at production time. The 628 application also describes a code reader and a network infrastructure for associating the information recorded on the sheet of material with the edge code.
An encoded sheet material, according to the 628 application, includes a sheet of material having a first surface, a second surface disposed opposite the first surface and an edge extending between the first surface and the second surface and peripherally about the sheet of material, the edge having indicia arranged thereon to form a code uniquely identifying the sheet of material. A system for managing an encoded sheet of material includes a code reader operative in conjunction with an encoded sheet of material for reading an edge code; wherein the encoded sheet of material has a first surface, a second surface disposed opposite the first surface and an edge extending between the first surface and the second surface and peripherally about the sheet of material, the edge having indicia arranged thereon to form a code uniquely identifying the sheet of material; a sheet processing apparatus for reading information from and/or writing information to at least one of the first and second surfaces of the encoded sheet material; and a processor in communication with the code reader and the sheet processing apparatus for associating the information with the edge code.
By providing each sheet of material with a unique edge identifier, any information that may be recorded on the sheet of material may be associated with that sheet of material. By placing the unique identifier on the edge, both surfaces are available for recording information. The edge marking can be made with a visible or an invisible ink. If the recording device includes an edge reader coupled to a processor with a memory, whenever a user makes a copy of an electronic file, the recording device reads the edge marking on each sheet of material used, and the processor associates that sheet of material with the electronic file. This association can be stored in memory. This feature is useful for tracking or monitoring physical copies of an electronic file. Additional information or meta data may also be associated with the electronic file.
The association information may be stored and used for other purposes, such as monitoring the number of copies made of a particular file, for monitoring the location of the copies and for monitoring the number of sheets of material used. The association information can be made or updated at any time. For example, if an electronic file is printed on a sheet of material with a unique edge marking, that association may be made and stored in a memory at the time of printing or later. If that recorded sheet of material is used to make a photocopy, an edge reader in the copier can make an association of the read edge marking of the xe2x80x9coriginal hard copyxe2x80x9d with the edge marking of the sheet of material used to make the photocopy. This information may be stored in memory and can be used to update the association information with the original electronic file and create a new association for the xe2x80x9coriginal hard copy.xe2x80x9d
Retrieving information associated with a sheet is accomplished by reading its edge identifier and querying the infrastructure to retrieve this information, given the identifier. Sheets of material may be pre-marked at production time. If pre-marked at production time, each sheet can be given a code identifying the ream to which it belongs as well as uniquely identifying that sheet. The code can include a portion identifying the ream, manufacturer, and other information that a user might require. Some reams of sheet material may be specially coded with special visible and/or invisible inks and used as special bond paper for financial instruments, for example. Indeed, some organizations may wish to reserve special reams of material.
Edge-readers can either be embedded in the recording devices (such as printers, facsimile machines, photocopiers, shredders, etc.) or affixed in work places (e.g. desktops). The edge readers may be coupled to a computer or network where the read association information may be read and/or written. The edge readers enable the automatic association of printed-sheet  less than - greater than  document. Users may also use any sheet of a document either to obtain related service by passing the sheet through an edge-reader, or to establish an association in a similar way.
The 628 application discloses an edge code scheme based on use of an offset mark. The distance of the offset mark from a reference mark on the edge (such as a corner of the edge or a baseline mark on the edge) is used as the code for the particular sheet material. Another code scheme disclosed in the 628 application is one where the identifier of any sheet is given by the combination of the unique identifier of the ream with the offset, which is unique within a ream. Because of the size of the marks on the individual sheets of material, many of the ubiquitous, inexpensive optical readers currently in the marketplace cannot effectively read these edge coding schemes (i.e., accurately measure the offset distance). It would be desirable to have a coding scheme that provides enough information redundancy and error handling that could be read with enough accuracy by currently available inexpensive optical readers.
An encoded sheet material, according to an embodiment of the invention, includes a sheet of material having a first surface, a second surface disposed opposite the first surface and an edge extending between the first surface and the second surface and peripherally about the sheet of material, the edge having indicia arranged thereon to form a code uniquely identifying the sheet of material; wherein the code comprises an offset mark located at an offset distance from a reference mark on the edge and a plurality of equally spaced clock marks disposed along the edge, such that the offset distance can be approximated by the product of the number of clock marks between the reference mark and the offset mark times the distance between successive clock marks. The reference mark can be a corner of the edge, or a specific mark on the edge (such as a thicker bar code type mark near a corner of the edge). A reference mark may be easier to detect than a corner of the edge. If the edge mark includes a ream identifer, the ream identifer can act as the reference mark. Alternatively, two reference marks can be provided, such that the offset mark will always be located between the reference marks.
This edge code can be easily and accurately read using inexpensive optical readers. A method of decoding an encoded sheet material includes scanning the edge code, detecting any offset marks on the edge, detecting any clock marks on the edge, counting the clock marks between a reference mark on the edge and the offset mark, measuring the distance between the offset mark and an adjacent clock mark, and computing the sum of the distance between the offset mark and the adjacent clock mark and the product of the number of clock marks between the reference mark and the offset mark times the distance between clock marks on left and right of the offset.
The offset distance can be determined approximately by the product of the number of clock marks between the reference mark and the offset mark times the distance between successive clock marks. To identify uniquely each sheet in the ream, the distance between the closest clock mark and the offset mark must be measured. The distance between the offset mark and the adjacent clock marks is a short distance. The shorter the distance to measure is, the smaller the error and the more reliable the sheet identifier reading.
An encoded sheet material, according to another embodiment of the invention, includes a sheet of material having a first surface, a second surface disposed opposite the first surface and an edge extending between the first surface and the second surface and peripherally about the sheet of material, the edge having indicia arranged thereon to form a code uniquely identifying the sheet of material; wherein the code comprises coincidence between a first plurality of equally spaced apart clock marks disposed along the edge and a second plurality of equally spaced Vernier marks, wherein the second plurality is less than the first plurality.
This edge code can also be easily and accurately read using inexpensive optical readers. A method of decoding an encoded sheet material, includes scanning the edge code; detecting any clock marks on the edge; detecting any Vernier marks on the edge; detecting coincidence between the detected clock marks and the detected, Vernier marks; determining an offset distance using the! coincidence between the detected clock marks and the detected Vernier marks.